High voltage (HV) battery systems for vehicles are manufactured by assembling battery cells, electrical connections and cooling equipment to provide a dense package with a minimum of open space. Pouch cells may be used in high volume, production HV battery systems. Pouch cells are generally planar layered ionic cells, such as lithium ion cells, that may be sandwiched between structural and/or thermal conditioning layers. A large number of cells are stacked in one or more rows and retained in a compressed array.
The rack, or tray, retaining the array of batteries should be robust to securely retain the battery cells in the vehicle. In addition, the battery cells may be assembled as a sub-assembly off line prior to being assembled to the vehicle. Handling a large, horizontally arranged stack of cells presents problems during assembly because the stack may bend or shift when moved. The cell array may be wired on one side of the stack of cells and may have cooling component parts on the opposite side. It is difficult to electrically connect the cells on one side of a stack of cells if the stack of cells is located close to an adjacent stack of cells. It is also difficult to connect the stack of cells to a cooling system if several batteries are stacked together in a closely spaced arrangement.
Batteries expand and contract during charging and discharging. Pouch cells may develop gas expansion pockets when charged if the cells are not kept under pressure. The gas expansion pockets reduce battery efficiency.
The disclosed battery module assembly and method of manufacturing a battery are directed to addressing the above problems and other problems as summarized below.